If you add the audio before anything else, you will have to add at least one image or text element with an animation of at least a few seconds in order to hear the audio start playing

Looks like the audio is over 8 minutes long. If you have already maxed out videoscribe's memory limit with excessive image file sizes, fonts or camera movements, then you might have problems which could include audio problems. Test the audio in a new scribe containing only 1 or 2 images.

If you have blutooth devices the sound might be going to a blutooth device instead of your computer speakers